1. Field of the Invention
The present invention relates generally to crossbows, and more specifically, to a crossbow having a lower rail for receiving a fore-end grip or the like.
2. Description of the Related Art
One of the most popular sporting rifles in the U.S. and many other parts of the world is the AR-15 rifle. The term “AR-15” was originally an abbreviation for the Armalite Model 15, a semi-automatic rifle that is commercially available to civilians. While the term “AR-15” has seen used as a trademark by Colt, generic rifles that use the original AR-15 configuration are available from a large number of manufacturers. The AR-15 civilian semi-automatic rifle and the M4 military automatic rifle are built upon the same basic platform. Among the reasons that the AR-15 is so popular is that it is modular in design, and therefore highly configurable and customizable. There are many suppliers who sell accessory items to add to AR-15 style rifles, including telescopic sights, buttstocks, grips, and the like. In addition, the accuracy of the AR-15 has made it popular with sport shooters and hunters. In particular, the trigger assembly of the AR-15 rifle has proved to be highly reliable in the field. The number of such AR-15 style rifles that have been sold in the U.S. has been estimated at 8 to 12 million. Owners of such rifles are constantly on the look-out for new accessories to use with such rifles.
Crossbows have also long been known in the archery field for use in hunting game. Crossbows have higher draw weights than conventional archery bows and fire arrows (or “bolts”) with greater speeds. As a result, crossbows usually have greater range than an archery bow. While there are some hunters own both a rifle and a crossbow, experienced hunters accustomed to hunting with rifles do not often branch into the use of crossbows, perhaps because they perceive that crossbows are too complex to operate.
When crossbows are configured for firing, the force exerted by the retracted bowstring can be in the range of approximately 100 to 200 pounds. A right-handed crossbow user typically positions a crossbow for firing by placing the butt end (often including a buttstock) of the crossbow against the user's right shoulder, grasping the trigger grip of the crossbow with the user's right hand, and grasping the barrel (or bolt rail) of the crossbow with the user's left hand ahead of the trigger. A left-handed user might do just the reverse. In either case, the user can better stabilize the crossbow by grasping the barrel forwardly of the trigger.
Due to advancements in technology and innovation, crossbows are capable of shooting arrows, or “bolts”, at ever-increasing speeds, thereby extending the range, and accuracy, of such crossbows. As noted above, state-of-the-art crossbows are now capable of exerting a draw force of approximately 200 pounds on the arrow (or bolt) during release. On the other hand, as arrow speeds increase, the manner in which a crossbow is supported during firing can have a greater effect upon the flight of the fired arrow. In order to maintain repeatable arrow shots, the manner in which the crossbow is supported during firing must be consistent from shot to shot.
Obviously, users of crossbows have different body sizes and different arm spans. Accordingly, users tend to grab the forward stock of the crossbow at different points, depending upon their size and build. Even a particular user may inadvertently grasp the crossbow differently for each shot, positioning his or her forward-most hand at a slightly different point along the stock from one shot to the next. Alternatively, if a user is supporting the underside of the crossbow stock upon a sandbag, for example, the user might not engage the sandbag at exactly the same point along the crossbow stock from one shot to the next. These variations in firing position may not have mattered as much in the case of older crossbows that produced relatively slower arrow speeds. However, Applicants have found that the increasing arrow speeds, and extended shot distances, produced by state-of-the-art crossbows effectively multiply the impact of such subtle variations in the support of the crossbow, thereby introducing noticeable errors in shot placement from one shot to the next.
Within the world of firearms, it is known to provide a heat guard/rail structure surrounding the barrel of a rifle. A user of the firearm can grasp the trigger grip of the firearm with one hand, and can grasp the heat guard with his or her other hand, forwardly of the trigger. For example, in U.S. Pat. No. 5,343,650 to Swan, an extended rigid frame receiver sleeve for a firearm is disclosed having both upper and lower rails. Swan's extended rigid frame receiver sleeve is joined to the firearm receiver and extends forwardly therefrom, surrounding the barrel of the firearm, while being spaced apart from the barrel as the sleeve extends forward. Swan describes the barrel of the rifle as being “free floating” relative to the extended rigid frame receiver sleeve. Swan states that hand guards mounted on the rigid frame receiver sleeve, rather than on the barrel itself, provide a much cooler grip to the shooter. Swan also explains that the “floating” barrel arrangement ensures that heat will not be transferred from the barrel to sensitive optics, electronics and other sensitive elements mounted upon the rigid frame receiver sleeve. Swan also states that the rigid frame receiver sleeve isolates the barrel, and prevents hand, sling, and bi-pod pressure from deflecting the barrel of the firearm; Swan further states that the free floating barrel avoids outside forces that could deflect the point of aim.
Unlike firearms, crossbows do not generate significant amounts of heat. Thus, in the case of crossbows, there is no need to isolate heat from the user's hands or from sensitive optics, and techniques used by firearm makers to isolate the heat of the barrel from a user's hands and/or accessories are not applicable. Moreover, until recently, crossbow firing speeds, shooting distances, and general accuracy, were all so limited that variations in the placement of the user's hands on the crossbow, or variations in the manner in which the crossbow was supported by a sandbag, bi-pod, or the like, were relatively insignificant. Accordingly, techniques used by firearm makers to prevent hand pressure or bi-pod pressure from deflecting the barrel of a firearm would not appear to be relevant to crossbows.
Accordingly, it is an object of the present invention to provide a crossbow adapted to be grasped by both hands of a user during firing while minimizing any variation in arrow flight that might otherwise result from the user's change of fore-end grip from one shot to the next.
Another object of the present invention is to provide a crossbow adapted to be partially supported by a bi-pod, sandbag, or the like during firing, while minimizing any variation in arrow flight, from one shot to the next, that might otherwise result from shifting the point at which the crossbow contacts the bi-pod, sandbag, or other stabilizing support.
Still another object of the present invention is to provide such a crossbow which achieves relatively consistent arrow placement for users of varying body builds and arm spans.
These and other objects of the present invention will become more apparent to those skilled in the art as the description thereof proceeds.